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Subject: [PATCH] sched_clock vs tsc_disable
From: Rusty Russell <rusty@rustcorp.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: Fri, 18 May 2007 12:42:23 +1000
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(Not sure who's code this is, but it's in 2.6.22-rc1-mm1):

If you set tsc_disable (eg "notsc" on cmdline), sched-clock.c gives a
divide by zero on boot.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff -r fd2ae7085ca2 arch/i386/kernel/sched-clock.c
--- a/arch/i386/kernel/sched-clock.c	Fri May 18 11:04:27 2007 +1000
+++ b/arch/i386/kernel/sched-clock.c	Fri May 18 12:12:24 2007 +1000
@@ -103,7 +103,7 @@ static void resync_sc_freq(struct sc_dat
 static void resync_sc_freq(struct sc_data *sc, unsigned int newfreq)
 {
 	sc->sync_base = jiffies;
-	if (!cpu_has_tsc) {
+	if (!cpu_has_tsc || tsc_disable) {
 		sc->unstable = 1;
 		return;
 	}